Coloured Glass-Ceramic Slabs via Controlled Crystallization
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Solution Overview
Problem
Existing methods for manufacturing glass-ceramic slab articles limit the range of aesthetic effects, particularly failing to achieve transparent or intense black colors, and result in slabs with limited hardness and resistance to scratching and alkaline attack.
Innovation Solution
A method involving a base mix with a preponderant amount (greater than 45% by weight) of a high-melting, 'hard' glass frit, sintered at high temperatures (1160-1230°C) and cooled within 4 hours to prevent devitrification, achieving a transparent aesthetic effect and intense coloration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional ceramic materials and glazes are used in the base mix, then the manufacturing process is simple and well-established, but the aesthetic effects are limited and transparent or intense black colors cannot be achieved
Solution Approach 1:
The patent changes the chemical composition parameters of the base mix by incorporating specific glass-ceramic materials with controlled crystallization properties and adjusting the particle size distribution and chemical ratios to enable transparent and intense color effects while maintaining manufacturability
Solution Approach 2:
The patent creates a composite base mix combining glass-ceramic materials with specific crystalline phases (such as magnetite for black color) and glassy matrices, where the composite structure enables both transparency and intense coloration that conventional single-material systems cannot achieve
2Illumination intensity
If pigments are added to the base mix to achieve coloration, then the aesthetic appearance is improved, but the color intensity and depth are limited and the slab appears opaque rather than transparent
Solution Approach 1:
The patent utilizes color changes through controlled crystallization of specific phases (such as magnetite crystals) within the glass-ceramic matrix, where the crystalline structure itself provides intense black coloration while the glassy matrix maintains transparency, eliminating the need for opaque pigments
Solution Approach 2:
The patent employs phase transitions during firing, where the glass-ceramic material undergoes controlled crystallization from an amorphous to a crystalline state, transforming the material's optical properties to achieve intense coloration while preserving transparency through the glassy phase
3Strength
If the base mix is fired at high temperatures to achieve melting and consolidation, then the slab structure is formed, but the glass frit undergoes devitrification and crystallization that reduces hardness and resistance
Solution Approach 1:
The patent adjusts the chemical composition parameters of the glass frit, incorporating specific oxides (such as Al2O3, SiO2, B2O3) in controlled ratios and adjusting the firing temperature parameters to optimize the balance between consolidation and preventing devitrification, thereby achieving high hardness and resistance
Solution Approach 2:
The patent uses a disposable mold or forming support that is removed after the slab is formed, allowing the glass-ceramic material to be fired and cooled without constraint, enabling precise control of the cooling rate to prevent devitrification while maintaining structural integrity
4Strength
If the cooling rate is slowed down to prevent devitrification and crystallization, then the glass frit maintains its amorphous structure and hardness, but the firing time is extended and productivity is reduced
Solution Approach 1:
The patent optimizes the cooling rate parameter by controlling the firing cycle, using a moderate cooling rate that prevents devitrification while maintaining reasonable productivity, and adjusts the chemical composition parameters of the glass frit to enhance its resistance to crystallization during cooling
Solution Approach 2:
The patent performs preliminary preparation of the base mix with optimized glass-ceramic materials and controlled particle size distribution before firing, which enables the material to resist devitrification during cooling without requiring extended firing times, thus maintaining productivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces glass-ceramic slabs with a transparent appearance that highlights added pigments, resulting in more intense and deep coloration, while maintaining high hardness and resistance to scratching and alkaline attack.
Implementation Method 1
a step of sintering the compacted and dried mix by means of firing to obtain the slab element
Implementation Method 2
glass ceramics have an amorphous phase which is typical of glass and one or more crystalline phases, which are typical of ceramics and are produced by means of so-called 'controlled crystallization'
Implementation Method 3
cooling, while ensuring that the duration of cooling from the maximum temperature to room temperature is limited to a maximum time period of 4 hours
Data Source
AI summary
Method for manufacturing coloured glass-ceramic slab articles from a base mix, including the steps of (a) preparing a mix comprising a colouring pigment, at least one binder and a preponderant amount of a glass frit having a specific composition, (b) distributing the mix in a forming support, (c) compacting the mix, (d) drying the mix, (e) sintering the compacted and dried mix by firing to obtain a slab article, and (f) cooling the articles under conditions such as to prevent—even partial—devitrification and/or crystallization of the glass frit. Also relating to a glass frit for manufacturing base mixes and a coloured glass-ceramic slab article obtained from the base mix.